Gang saw



Aug. 7, 192

E. P. ARMSTRONG GANG SAW Filed May 6, 1926 3 Sheets-Sheet Hill im d l 0 o E. P. ARMSTRONG Aug. 7, 1928.

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E. P. ARMSTRONG GANG SAW Filed May 6, 1926 3 Sheets-Sheet 5 Inl/@H751 Patented Aug. 7, 1928.

UNITED STATES PATENT OFFICE.

GANG sAw.

Application led May 6, 1926. Serial No. 107,138.

My invention relatesv to that type of gangsaw commonly used in saw mills, which comprises a reciprocated sash carrying a plurality of spaced saws.

The weight of this sash, together with its saws, is considerable, weighing approximately vthree tons, `and the saw-sash is reciprocated at a relatively `high speed, approximately 250 strokesv per minute. Hence, this great mass, and the relatively great lineal speed at which it is reciprocated, tends to impose a great strain on the driving mechanism of the gang-saw. This driving mechanism commonly comprises a pitman connected to a crank-pin, and while these parts might be made ofl sufficient size to safely withstand said stresses, even then there would be great difficult-y encountered in designing boxings which would stan d up under said conditions. Besides, the pounding .incidental tothe reciprocation of said mass tends to loosen the foundations.

The objectV of my invention is to provide means connected to said saw-sash by which the shocks dueto the great mass and momentum shall be substantially absorbed, and all undue stress on the crank-pin of the gang eliminated.

I attain my object by connecting the said saw-sash to compression cylinders, and since a common construction of said gang-saw includes adjustable guideways, and guideheads, operatingl therein, to which one end of said saw-sash is connected, one specific mode of carrying my invention into practice is to provide said guideways 'with frame extensions and mounting compression cylinders on said extensions; the compression cylinders having pistons, which are connected to and axially alined withthe path of motion of the guide-heads. In that way the guideways are arranged to suit all requirements of the gang saws without throwing the pistons and their connection with the sawsash out of alinement. Furthermore, the opposit-e ends of the compression cylinders arey each provided withV a valve controlled `fluid inlet; and a fluid passage connects .said ends, said fluid passage vbeing `provided with a valve.

A further incidental object of myinvention is to provide two cushioning cylinders for the sash and saws carried thereby, said cushioning cylinders being arranged so as to-lie in a plane with .the top slides for said sashk and being connected'by a relatively stiffmember yadapted to sustain a substantialy amount of compression or tension. Supportlng devices are provided exteriorly of said guides and support said cylinders, said supporting devices being carried by the frame of the machine. Said cylinders are connected by relatively stiff members adapted to sustain a high degree of compression and tension, thus providing mutual supports -for vsaid cylinders to prevent their collapsing inwardly or yielding outwardly, that is, towards each other or from each other.

Further details of construction and mode of operation of my invention are hereinafter described with reference to the accompanying drawings, in which:

F l is a fragmentary elevation of a gang-saw embodying my invention, portions of the devices being shown as broken away to disclose structural details;

Fig. 2 is a fragmentary elevation of a portion of said device on a larger scale, the parts being foreshortened; said figure disclosing details of the supports for said sashes and the connections with said cushioning elements; c

Fig. 3 is a longitudinal vertical section taken on the line 3 3 of Fig. l, and in addition shows a cant or timber passing through said saws;

Fig; 4 is a larger scaled foreshortened section taken substantially on the line i--4 of Fig. l; i

Fig. 5 is a vertical section taken through a gang-saw cushioned by a cylinder mounted below said saw, which arrangement is a modification of my invention;

Fig. 6 is a further vertical section disclosing a further modification of my invention in which the cushion cylinder is connected to the saw frame through a rocker arm;

Fig. 7 isa horizontal section taken on the line 7-7 of Fig. 5; and

Fig. 8 is a horizontal section taken on the line 8 8 of Fig. 6.

The gang saw embodying my invention comprises a frame @which is mounted upon a concrete foundation b. Intermediate supporting members Z2 are interposed between the concrete foundation and the base a of the frame, said auxiliary supporting inembers are preferably made of wood so as to have a slight amount of resiliency and thus eliminate a portion of the jar given to the foundation. Holding-down bolts b2 are provided, said bolts passing through the base a of the frame, the auxiliary supports b and into the concrete foundation Z).

Two crank shaft boXes c are provided for the crank shaft CZ; upon said crank shaft a driving pulley, e, is fastened and a fly wheel c is also commonly provided, for the usual purpose. Said crank shaft also carries a crank disc d and a crank pin d2; said shaft, disc, and pin usually being made of an integral forging to secure the maximum amount of strength.

Slidably mounted between the sides of said frame a is a saw-carrying sash f which is substantially rectangular and carries a plurality of spaced saws g. A wrist pin f is usually formed as an integral portion of said sash and a pitnian 7L connects said wrist pin and the crank pin d2, as shown lin Fig. l. Said sash carries guide pins at the lower end and t" a" at its upper end which are journaled in guide boxes i? and respectively which are slidably carried in the top and bott-om slides l7' and 7" respectively. Said bottom slides j pivotally carried by the sides of frame a, upon pivots 7.2 and the top slides are carried by pivots 7c. free pivotal movement about Iits pivot if., while each top slide 7c is held in adjusted position by set screws Z which pass through slotted holes jg in the slide and are secured in the frame, thus permitting a degree of angular' adjustment for the said top slides. The usual mechanism is provided for oscillating the bottom slides j", said mechanism comprising the rock shaft m, which is connected to the crank shaft cl, by an auxiliary pitman m', which connects the auxiliary crank pin (Z3 thereon with the crank arm m2 on the rock shaft m. Said rock shaft also carries other crank arms 'm3 which are connected with the lower slide j', through longitudinally adjustable rods m4 provided with a turn-buckle m5 provided for making this adjustment. The rotary oscillation of said rock shaft m causes the corresponding inotion of said arms mi" which results in the oscillation of said lower slides j about their pivots. rllhe supports for the said pressure cylinders 1i, are the top slides upon each frame side, and the length of the slides is increased so that they extend above the top of the frame a, as shown clearly in Fig. 4l. Pistons o reciprocate within the bore of each of said cylinders a, and are connected to the pins 'i' of the sash f by piston rods p. A by-pass Q is provided in each of said cylinders which opens into the cylinder at its opposite ends; and a manually operatable valve fr is provided in each of said ley-passes for controlling the iiow of lluid therethrough. One of said valves is operated by theVbell-crank lever r and the other by the levers ,4. A link 'r3 connects the bell-crank lever r with the lever rt, and these bell- Each bottom slide is permittedl nk levers are operated by a handle r2., so that the said valves may be opened or closed simultaneously. Said by-passes g and the manually operated valve 7" is provided to permit the operating devices to be started up without being required to compress the cushioning fluid contained in said cylinders, said fluid content usually being air.

When the gang-saw is started up, said valve r is opened, and thus the fluid is permitted to flow through said by-pass varound said piston. After the machine has attained sufficient speed, said valve r is closed and the pistons of the cylinders a tend to support the sash independently of the pjitman fr..

The elimination of said cushioning devices atvstarting speed do not permit the frame to be vibrated by the reciprocating sash, because its speed is so low that the pounding is not severe. The bell crank r and the operating lever r2 are arranged so as to hold the valve closed and said valves are only opened when said lever r2 is lifted upwardly by the operator. Loss of fluid pressure in 'said cylinder through the packing s' for the piston rod n or otherwise is con'ipensated for through the vents t and t in each of said cylinders, said vents being controlled by check valves u and u', which are arranged to permit fluid to enter said cylinders but to prevent its return flow' therefrom.

Said cylinders a are connected by an X- shaped compression member o which is stiff and adapted to sustain a relatively large amount of compression. Said top slides are supported eXteriorly by the frame sides a, as shown in Fig. l and thus by bracing Said slides and said cylinders against each other, said cylinders are prevented from collapsing towards each other by the stresses imposed thereon due to the reciprocation of the'shaft and the saw carried thereby.

As shown in Fig. 3 feeding rolls w are provided. for the cant or timber m to be cut, said rolls operating continuously. Additional top press rollers are usually provided for holding said cant or timber to said bottom rollers to prevent slippage; said top rollers form Vno part of my invention, however, and thus are not shown because they would otherwise cover structural features of the gang-saw with which my invention is not concerned. v

As is apparent the weight of the reciprocating mechanism is supported bet-Ween two opposed volumes of compressiblevfluid and thus the hammering caused by the forcing upwardly and downwardly of said sash and the saws carried thereby will be minimized and substantially eliminated by said cushions. By arranging said cylinders upon said top slides they are always in alinement with said slides to prevent the binding or pinching of said piston rodsp for the pistons, in said cushion cylinders, and the load lie which they are called upon to support thus exerts its stresses substantially longitudinally of said rods so that said rods are subjected merely to tension and compression and to little or no flexure. The top slides are also thus required to withstand straight tension and compression stresses, and little or no flexure or combination stresses and thus the machine is admirably adapted to withstand and support the unusual stresses which machines of this character are subjected to.

In the modifications in my invention shown in Figs. 5 and 6 all of the details of the gang-saws are the same as those in the previous figures andthus I will refer to the same by the reference characters given to the similar parts in said previous figures.

In Fig. 5 the lcushion cylinder n? is connected to the crank pin CZ: on the crank disc (Z by an auxiliary connecting rod 2, one end of said rod being connected to the end of the connecting rod 7i. and its other end being connected to a sliding block 3. Said latter block is slidably mounted between opposed guiding flanges l carried by the trame af of the machine. The piston rod p2 for said cylinder n@ is connected to said block which block thus serves as a cross-head.

In Fig. 6 the piston rod p3 for the cylinder a3 is connected to the rocker arm 5 through a sliding block 6 and to pivoted auxiliary connecting rod 7. Said sliding block 6 is slidabiy engaged by guiding ianges 8 as shown in Fig. 8. Saidfrocker arm 5 pivotaliy mounted at its middle upon a bracket 9 carried by the frame 1H and the opposite end of said rocker arm 5 is connected to the guide boxjg by a rod 10, asshown in Fig. G.

The cylinders a: and n 1n said modifications ai'e exactly the same as shown in previous drawings and serve in a similar manner in resisting the pulsating blows caused by the reci procat-ion of the enormously heavy saw sash.

I claim:

l. In a gang-saw having a reciprocating saw-sash, an adjustable guideway at each 'side oi said saw-sash, a guide-head operating in each guideway to which guide-heads one end of said saw-sash is connected, each guideway having a frame extension, a coinpression-cylinder mounted on each of said i'rame extensions and a piston in each compression-cylinder, the piston being connected to and axially-alined with the path of motion of its related guide-head, each compression-cylinder being provided with a valve controlled fluid-inlet at both ends, a fluid passage lconnecting said ends, anda valve in said passage, means for operating the latter valves in unison. 1

2. In a gang-saw having a reciprocating saw-sash, an adjustable guideway at each side oi said saw-sash, and a guide-head operating in each guideway to which guideheads one end of said saw-sash is connected, each guideway having a frame extension, a compression-cylinder mounted on each of said frame extensions and a piston in each compression-cylinder, the piston being connected to, and axially-alined with the path of motion of its related guide-head, and each compression-cylinder being provided with a valve-controlled fluid-inlet at both ends, a fluid passage connect-ing said ends, and a valve in said passage, and means for operating the latter valves in unison, and each of said compression-cylinders being arranged to overhang the center line of motion of the guide-head with which its piston is connected, and a rigid brace connecting said cylinders.

3.. In a gang-saw comprising a frame and a reciprocating saw-sash, a guide-way adjustably mounted on said frame, a guidehead operating in said guide-way to which one end of said saw-sash is connected, a compression cylinder carried by said guide-Way,

' a piston in said compression cylinder, and a rod connecting said piston with said guidehead, sait guide-way being adapted to permit limited angular adjustment thereof with respectto the line of motion of said sawsash, and whereby said saw sash in recipocating will be given an oscillatory movement Without creating lateral and fiexure stresses.

4. In a gang-saw comprising a frame and a. reciprocating saw-sash, a guide-way pivoted on said frame, a guide-head operating in said guide-way to which one end of said saw-sash is connected, a compression cylinder carried by said guide-way, a piston in said compression cylinder, and a rod connecting said piston with said guide-head, said guide-way being adapted to permit limited angular adjustment thereof with respect to the line of motion of said saw-sash, and whereby said saw-sash in reciprocating will be given an oscillatory moven'ient without creating lateral and fiexure stresses.

5. In a gang-saw comprising a frame and a reciprocating saw-sash, guide-ways adjustably mounted at each side of said saw-sash on said frame, guide-heads operating in-said guide-ways to which one end of said sawsashkis =connected, compression cylinders carried by said guide-ways, pistons in said compression cylinders, rods connecting said pistons with said guide-ways, and a rigid brace connecting said cylinders, said guide-Ways being adapted to permit limited angular adjustment thereof with respect to the line of motion of said saw-sash, whereby said sawsash in reciprocating `will be given an oscillatory movement Without Acreating lateral and flexure stresses.

EDWARD P. ARMSTRONG.

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